checkpoint ngfw

Author: runming QQ: 226399587 http://blog.csdn.net/runming918As an important mechanism in oracle, SCN (System Chang Number) plays an important role in Data recovery, Data Guard, Streams replication, and synchronization between RAC nodes. Understanding the operating mechanism of SCN can help you gain a deeper understanding of the above functions.Before understanding SCN, Let's first look at how data changes in oracle transactions write data files:1. Start the transaction;2. Find the required data

according to the table:Initial time Load phase: During the initial data load phase, the extract process extracts data directly from the data table on the source side.Synchronization change capture phase: After initial data synchronization is complete, the extract process is responsible for capturing the source-side data changes (DML and DDL)Goldengate does not support DDL operations on all databasesThe extract process captures all configured object changes that need to be synchronized, but only

Instance recovery is used to recover from a crash failure or an instance in a parallel server environment fails, so instance recovery can refer either to crash recovery or to instance recovery in a parallel server environment (as long as one surviving instance can recover one or more failed instances). The goal of instance recovery is to restore the block of data in a failed instance in the data buffer and close the open thread. Instance recovery uses only the online archive log and the current

ASSERT syntax instance, assert syntax ASSERT Syntax ASSERT [[ID group [SUBKEY sub] [FIELDS val1 val2...] CONDITION] log_exp. Extras: 1... ID group 2... SUBKEY sub 3... FIELDS val1 val2... 4... CONDITION Effect This statement defines an assertion. any logical expression can be specified for log_exp. when the program reaches an active assertion, the logical expression is evaluated and the program execution continues from the statement after ASSERT only if the result of log_exp is true. after an in

. Checkpoint 2.1 First mark a dirty page in shared buffer 2.2 to the page that is marked as dirty, call write If the shared buffer is large and the business shape causes the database to produce dirty pages quickly, the checkpoint will instantly produce a lot of OS dirty page. 2.3 To related FD, call Fsync, persistent The database checkpoint process calls Fsy

active database and the passive database.Storage content:The contents of the mailbox database and the shared folder are primarily stored in Exchange Server 2010, and the mailbox database is the most accessible, and as for public folders, it's easy to understand that in versions prior to Outlook 2007, for things like free/busy information and offline Address Book (OAB) Download and other functions, you need to use the public folder. This means that if the enterprise is using the Outlook2007 vers

also temporarily written to the redo log_buffer, the file will be synchronized to the file only when a certain event is triggered. The size of the transaction log file is closely related to the overall IO performance of Innodb. Theoretically, the larger the log file, the less refresh actions required by the Buffer Pool, and the higher the performance. However, we cannot ignore another thing, that is, the recovery after the system Crash. Innodb records every modification made to the data and ind

exist in the buffer cache. This is clearly unreasonable. As you can see from here, this starting point actually shows that the dirty blocks in the buffer cache that correspond to the redo entries in the log file before this starting point have been written to the data file, so that there is no need to consider the recovery after the instance crash. And after this beginning of the redo items corresponding to the dirty block is not actually written to the data file, if in the recovery after the

Label:MySQL Engine Features · InnoDB Crash Recovery processIn the previous two monthly report, we introduced the knowledge of InnoDB redo log and undo log in detail, and this article will describe the main process of InnoDB in the case of crash recovery. This article code analysis is based on the MySQL 5.7.7-RC version, the function entry is innobase_start_or_create_for_mysql , this is a very verbose function, this article only involves and crash recovery related code. Before reading this articl

log file copy (a copy of the log file at the end of the dump), redo the completed transaction, and undo the unfinished transaction.The log files are scanned first to identify the committed and incomplete transactions at the time of the failure, and to record them into the redo queue and the undo queue, respectively.The log file is then scanned for redo processing of all transactions in the redo queue. Reverse-Scan the log file for undo processing of all transactions in the undo queue.Recovery o

Playback The system restarts the playback log, only to scan the log file from the back forward, and to rollback the data in the log record for all transactions that do not commit. CheckPoint To replay the log as described above, all log files need to be scanned, and the log files cannot be deleted. But in practice, we can see that if a transaction has already been commit, the previous log record can be done without playback. Therefore, the concept of

When the Oracle kernel finds that an instance is dead and the corresponding thread opens the status bit in the control file, it will automatically restore the instance. When the Oracle kernel finds that an instance is dead and the corresponding thread opens the status bit in the control file, it will automatically restore the instance. Instance recovery is used to recover failed instances or failed instances in the parallel server environment, therefore, instance recovery can refer to both

When talking about the transaction log, you have to talk about the Checkpoint, or CKP for short. The transaction log and the Checkpoint both exist for the rapid recovery of the database. We need to know what the checkpoint is and what it has to do with the transaction log. What does CKP do? In general, data changes are not directly written to the mdfndf data file

the current requirements. You can set the maximum number of available instances to limit the amount of memory that SQL server uses to lock. The default value is 0, which allows the SQL Server to dynamically request the allocation and revocation of locks based on system requirements. SQL Server allows up to 40% of the memory to be locked. Keep the locks parameter as the default value 0 and allow SQL Server to allocate locks as needed. This option is an advanced option and can only be set with sp

Instance recovery is used to recover failed instances or failed instances in the parallel server environment, therefore, instance recovery can refer to both crash recovery and instance recovery in the parallel server environment (one or more failed instances can be recovered as long as one surviving instance ). The target of instance recovery is to restore the data blocks of failed instances in the data buffer and disable the running threads. Only online archiving logs and current online data fi

Tags: IMA crash memory logs ordered also data class CEOAs with Oracle, SQL Server also makes instance recovery (Instance Recovery) when non-conformance is turned off, and this article describes some of the SQL Server instance recovery knowledge based on the article in the stack overflow. Original link:https://stackoverflow.com/questions/41932735/sql-server-instance-recovery about Oracle's instance recovery reference before the blog post: http://www.cnblogs.com/leohahah/p/6973600.html First look

write SCN and commit scn to the data block header, the checkpoint also writes SCN to the control file and data file header, the user's DML and COMMIT only write SCN and commit scn to the data block header without updating the SCN of the control file and data file, the SMON rollback starts from the file header's SCN, that is, from the previous checkpoint. The SMON rollback is a data block not identified as

Introduction to backup implemented by perforce Creation Method: On the perforce server, use the-JC flag to create the server. By default, the P4d-r root-JC is saved as the checkpoint. N file and journal. n-1 in the root directory of the perforce program to record historical data at the same time. The last checkpint. N and this journal. This is all the information of the current checkpoint database. For ex

Oracle SCNSystem Chang Number) is an important mechanism in Oracle, it plays an important role in Data recovery, Data Guard, Streams replication, and related synchronization between RAC nodes. Understanding the operating mechanism of SCN can help you gain a deeper understanding of the above functions. Before understanding Oracle SCN, Let's first look at how data changes in Oracle transactions write data files: 1. Start the transaction; 2. Find the required data block in the buffer cache. If no d

Brief introductionThe recent test server for data archiving, during which the programmer found a problem, lack of space, I look for reasons to find the log file explosion. The database is then changed to a simple recovery model, but this problem still exists. After querying the data, it was found that the log file still increased in simple mode.Simple conceptSimple recovery mode is also called "Checkpoint with Truncate log", in fact, the name is more